ABSTRACT
Amorphous As2S3, As2Se3 and As1Se99 bulk glasses and thin films were prepared by the melt quenching technique and vacuum thermal evaporation, respectively, on different substrates. The density (ρ) - determined by the simple and cheap method of precise weighting, refractive index (n), structural arrangement - inferred from Raman spectroscopy, and nanohardness (H ind) were determined for all the studied materials in both bulk and thin film states. It is found that regardless of the chemical composition, the bulk glass density, refractive index and nanohardness are higher in comparison with those of the corresponding virgin and by annealing relaxed thin films, and the observed differences are discussed. The almost negligible influence of the substrate on the thin films density, structural arrangement and nanohardness, was observed.
ABSTRACT
In this study, we investigate the preparation of surface pattern of functional groups on poly(lactide) (PLA) surfaces through the controlled deposition of core-shell self-assemblies based on functionalized PLA-b-PEO amphiphilic block copolymers from selective solvents. Through grafting RGDS peptide onto the functionalized copolymer surface, the presented approach enables to prepare PLA surfaces with random and clustered spatial distribution of adhesive motifs. The proposed topography of the adhesion motif was proved by atomic force microscopy techniques using biotin-tagged RGDS peptide grafted on the surface and streptavidin-modified gold nanospheres which bind the tagged RGDS peptides as a contrast agent. The cell culture study under static and dynamic conditions with MG63 osteosarcoma cell line showed that the clustered distribution of RGDS peptides provided more efficient initial cell attachment and spreading, and resistance to cell detachment under dynamic culture compared to randomly distributed RGDS motif when with the same average RGDS peptide concentration.
Subject(s)
Cell Adhesion/drug effects , Lactates/chemistry , Nanostructures/chemistry , Polyethylene Glycols/chemistry , Biomimetics , Cell Line, Tumor , Gold , Humans , Metal Nanoparticles , Microscopy, Atomic Force , Oligopeptides , Protein Binding , Streptavidin/chemistry , Surface PropertiesABSTRACT
The paper presents the results of geochemical investigations carried out in the city of Prague. Czech Republic, between the years 1994-1997, by the Czech Geological Institute, National Institute of Public Health and Hygiene Stations of Prague. Exposure assessment for children as the most sensitive population, based on soil ingestion pathway, indicates that lead is the major pollutant of concern, especially in the central regions of the city. Direct exposure assessment was done by analyzing blood and urine samples collected from children aged 3-6 years. Blood lead levels were the only biomarker significantly higher as compared to the control group (32.1 +/- 17.4 microg/l, 25.1 +/- 15.4 microg/l). This pilot study supports the establishment of a new sub-system within the already existing System of Monitoring the Environmental Impact on Population Health of the Czech Republic.
Subject(s)
Environmental Exposure/adverse effects , Environmental Monitoring/methods , Metals, Heavy/adverse effects , Soil/analysis , Adolescent , Adult , Child , Child, Preschool , Czech Republic , Female , Health Status , Humans , Male , Metals, Heavy/analysis , Middle Aged , Pilot Projects , Risk Assessment , Sampling Studies , Sensitivity and Specificity , Urban PopulationABSTRACT
The purpose of this investigation was to determine the test-retest response consistency rate on a semantic memory task in persons with dementia of the Alzheimer type (DAT). Ten mildly and 13 moderately impaired DAT subjects and 14 normal controls matched for age, years of education, and estimated IQ participated in this study. The Peabody Picture Vocabulary Test (PPVT) was administered twice to each subject with a 7-day intertest interval. The mild and moderate DAT subjects responded inconsistently to significantly more PPVT items than normal controls. When the effects of guessing were considered, moderate DAT subjects gave significantly more inconsistent PPVT responses than normal controls and mild DAT subjects showed a trend toward giving more inconsistent responses. These results substantiate the conclusion that the impairment of specific conceptual knowledge in DAT subjects cannot be reliably measured with a single administration of a semantic memory task such as the PPVT.
